There are several methods known as biometrics for recognizing or identifying an individual. Some of these methods involve imaging of the face or eye and analyzing the facial features, retinal vascular patterns of the eye or patterns in the iris of the eye. A technique for iris recognition is described in U.S. Pat. No. 4,641,349 to Flom et al. and in U.S. Pat. No. 5,291,560 to Daugman. The systems described in these references require the person being identified to hold at least one of their eyes in a fixed position with respect to an imaging camera that takes a picture of the eye.
In U.S. Pat. No. 5,717,512 there is disclosed an automated teller machine which relies upon three cameras to identify the user of an automated teller machine. The first two cameras are wide field of view cameras which find the subject's head and locate the eye position in the image. A three-dimensional position in space for the eye is calculated from the images. From that information a narrow field of view camera is directed to that position. The narrow field of view camera then takes an image of the eye from which identification can be made. Although such a system has been made to work quite well, the use of multiple cameras is expensive. Furthermore, this system occupies significantly more space than a single camera system would occupy. Thus, there is a need for a single camera system which can acquire an image of the eye useful for identification of the individual. This system should be compact, easy to use and minimally intrusive.
The popularity of the internet has opened the marketplace for electronic commerce and electronic banking. As people desire to make more expensive transactions over the internet a demand has developed for a device to assure that the person at the customer's computer is truly the person who is authorized to conduct the transaction. Iris identification has proven to be a reliable way to identify individuals. Additionally, the use of video cameras connected to personal computers has grown as cheaper digital cameras have become available. Thus, the cameras are available to provide images of computer users for iris identification. However, those cameras can only be used if the user is properly positioned for a clear, well-focused image. Hence, there is a need for a device for directing the user to the proper position from which a well-focused image of that person can be made.
Holographic optical elements having a transmission hologram are well known devices on which a viewer can see different images or portions of images according to the angle at which he views the hologram created in the holographic optical element. However, prior to the present invention the art has failed to recognize that such devices could be used to direct a user to position his eye within a selected volume of space surrounding a focal point of a camera that is used to take an image of the user's eye.